Device for continuously casting metals, especially steel

ABSTRACT

A device for continuously casting metals, especially steel, consists of multipleconsecutive segments ( 1 ) which each form the strand guide for casting strands of different widths ( 4 ), with roller pairs ( 2 ). The rollers are rotationally mounted on segment frames ( 5; 6 ), these segment frames ( 5; 6 ) each being braced with strand guide frames ( 10 ) on both sides. The aim of the invention is to reduce profile increases in the cross-section of the casting strand ( 4   d ) in the residual solidification area ( 4   b ), by providing a power mechanism ( 13 ) at least on the fixed side of the segment frame ( 5 ) of a segment ( 1 ), between the segment frame ( 5 ) and a transversal member ( 11 ) connecting the strand guide frames ( 10 ) on the two sides. Said power mechanism is situated approximately on the middle strand axis. The power transmission element ( 13   a ) of the power mechanism acts upon the segment frame ( 5 ), while its base ( 13   b ) is supported on the transversal member ( 11 ).

BACKGROUND OF INVENTION

invention pertains to a device for continuously casting metals,especially steel, with several successive segments, each of which has apair of rolls, consisting of an upper and a lower roll, the segmentsforming a strand guide for cast strands of different widths, where therolls are rotatably supported on tie-bars of a segment frame, and whereeach of the tie-bars is braced on both sides by strand guide frames.

Devices of this type are known, for example, as guides for thin metalstrip (EP 0 941 787 A1). In this case, however, an adjusting device foradjusting the crown bow of the roll gap is provided for a pair of guiderolls, which forms a roll gap. A device of this type cannot be used tosolve other problems.

The profile of a cast slab in the residual solidification area of thecast strand is essentially an image of the geometry of the roll gap.Different strand widths and casting speeds lead to different rolldeflections and to different deflections of the tie-bars of the segmentframe and thus to a slab profile with a variable camber.

In the area of the soft reducing section, the deflections of the rollsand tie-bars are determined by the location of the tip of the crater, bythe thickness reduction setting, and by the grade of steel. It alsohappens that, in the case of slab systems with a lengthwise cuttingdevice (single or multiple lengthwise cutting), the lengths of cut slabwhich are sent to the rolling mill will have various wedge-like shapesbecause of the camber of the original slab. These variable shapes leadto problems in the mill when a very thin strip is to be obtained as theend product.

SUMMARY OF THE INVENTION

The invention is based on the task of decreasing this variable camber inthe final solidification area, so that the problem described aboveduring the following rolling process will no longer occur.

Proceeding from the device described above, the indicated task isaccomplished according to the invention in that a force-exertingmechanism, located approximately on the center axis of the strand, isprovided at least on the fixed side of the segment frame, between thesegment frame and a transverse tie-bar, which connects the two strandguide frames. The force-transmitting element of this force mechanismacts on the segment frame and is supported at the other end on thetransverse tie-bar. Because the rolls can thus be made to flex, it ispossible to reduce the camber of the profile by bending the segmenttie-bar in the opposite direction. The profile camber of the cast strandrequired for rolling can thus be obtained. Depending on where the tip ofthe crater is, it is also possible to use the force mechanism toinfluence the deflections of the roll and of the tie-bar as a functionof the load on the segment in such a way that the resulting camber ofthe profile does not lead to any problems in the rolling mill even incases where the slabs are cut lengthwise.

The force mechanism can consist of a single-acting plunger.

In another embodiment, the force mechanism consists of a double-acting,hydraulic piston-cylinder unit.

In accordance with additional features, it is proposed that the forceexerted by the force mechanism can be controlled automatically as afunction of the load being exerted on the segment by the cast strand. Asa result, it is possible to prevent excessive loads from acting on thesegment frame.

This automatic control can also be implemented in that, as a function ofthe load being exerted on the segment, the force exerted by the forcemechanism can be transmitted to the deflection of the support roll andthe tie-bar to oppose the expected camber of the cross section of thecast strand.

It can also be advantageous in certain situations for the force exertedby the force mechanism to be adjustable force on the floating side ofthe segment. The advantages which can be achieved will be the same as orsimilar to those obtained when the force mechanism is located on thefixed side of the segment.

Another application of the basic idea of the invention consists in thatthe force exerted by the force mechanism can be adjusted simultaneouslyon the fixed side and on the floating side of the two opposing segmentframes.

It can also be advantageous to assign several force mechanisms to eachsegment frame. As a result, the curvature of the tie-bar can be adjustedmore exactly.

It is conventional in practice to install a lengthwise cutting devicedownstream from the segments. Adjusting the profile camber just upstreamof the lengthwise cutting device means that the profile can be adjustedprecisely to the shape required for rolling before the slab is cut.

A special embodiment, furthermore, consists in that the characteristiccurves which describe the deformation of a segment are filed in the formof tables in a computer, and that the force exerted by the forcemechanism can be called up from the stored values in correspondence withthe load being exerted on the segments. As a result, it is easy to useboth empirical values and values based on the design dimensions tocalculate the most suitable curvature.

BRIEF DESCRIPTION OF DRAWING

The single FIGURE of the drawing shows a front view of a support rollsegment, that is, a view perpendicular to the direction in which thecast strand is traveling, as will be explained below in greater detail.

DETAIL DESCRIPTION OF THE DRAWING

The device for the continuous casting of metals, especially of steel,consists of several segments 1, which succeed each other in thedirection of travel of the strand. To guide the cast strand 4, eachsegment has a pair 2 of rolls, which can consist of split rolls 3,comprising an upper and a lower roll. The width 4 a of the cast strand 4can vary. To indicate the point at which the position of the segment 1is located, the cast strand 4 has a strand shell 4 c in the area ofresidual solidification 4 b. The two rolls of the pair 2 are rotatablysupported on segment frames 5, 6; the segment frame 5 is on the fixedside, whereas the segment frame 6 is on the floating side. The twosegment frames 5 and 6 can be moved toward each other by means oftraction cylinders 7 so as to take into account the thickness 8 of thecast strand 4. The segment 1, consisting of the segment frames 5 and 6and the traction cylinders 7, is attached on both sides by means ofclamping cylinders 9 (not illustrated in detail) to the strand guideframes 10.

At least one force-exerting mechanism 13 is provided approximately onthe center axis 12 of the strand, this mechanism being installed atleast on the side of the segment 1 with the fixed segment frame 5, i.e.,between the segment frame 5 and a transverse tie-bar 11, possibly addedfor the purpose, which connects the two strand guide frames 10. Theforce-transmitting element 13 a of this force-exerting mechanism acts onthe segment frame 5, and the base 13 b of the mechanism is supported onthe transverse tie-bar 11. The segment 1 and the transverse tie-bar 11are provided at least in the area of the residual solidification 4 b.The force mechanism 13 can consist of a single-acting plunger 14 or of adouble-acting, hydraulic piston-cylinder unit 15.

The force exerted by the force mechanism 13 can be controlledautomatically as a function of the load being exerted on the segment bythe cast strand 4. The force exerted by the force mechanism 13 can alsobe made adjustable on the floating side 6 of the segment 1. In specialcases, it can be advantageous for the force exerted by the forcemechanism 13 to be adjustable simultaneously on both the fixed side 5and the floating side 6 of two opposite segment frames 5, 6.

Several force mechanisms 13 can be assigned to each of the segmentframes 5, 6.

A lengthwise cutting device of conventional design follows the segment 1with the transverse tie-bar 11 and the force-exerting mechanism 13.

The characteristic deformation curve 19 of a segment 1 is filed in theform of tables in a computer, and the force to be exerted by the forcemechanism 13 can be called up from the stored values in correspondencewith the load being exerted on the segment.

The cross section 20 of the transverse tie-bar of the segment 1 is to beselected as a function of the load exerted on the segment to minimizethe force which must be exerted by the force mechanism 13.

List of Reference Numbers

-   1 segment-   2 pair of rolls-   3 split roll-   4 cast strand-   4 a variable width-   4 b residual solidification area-   4 c strand shell-   4 d cross section of the cast strand-   5 segment frame, fixed side-   6 segment frame, floating side-   7 traction cylinder-   8 thickness of the cast strand-   9 clamping cylinder-   10 strand guide frame, one on each side-   11 transverse tie-bar-   12 center axis of the strand-   13 force-exerting mechanism-   13 a force-transmitting element-   13 b base-   14 plunger-   15 piston-cylinder unit-   19 characteristic deformation curve-   20 cross section of the tie-bar

1. Device for the continuous casting of metals, especially of steel,comprising several successive segments, each of which has a pair ofrolls, consisting of an upper and a lower roll, the segments forming astrand guide for cast strands of different widths, where the rolls arerotatably supported on the tie-bars of a segment frame, and where eachof the tie-bars is braced on both sides by strand guide frames, wherein,at least on fixed side of the segment frame (5), a force-exertingmechanism (13), lying approximately on the center axis (12) of thestrand, is provided between the segment frame (5) and a transversetie-bar (11), which connects the two strand guide frames (10), theforce-transmitting element (13 a) of the force-exerting mechanism actingon the segment frame (5), whereas the base (13 b) of the force mechanismis supported on the transverse tie-bar (11).
 2. Device according toclaim 1, wherein the force-exerting mechanism (13) consists of asingle-acting plunger (14).
 3. Device according to claim 1, wherein theforce-exerting mechanism (13) consists of a double-acting, hydraulicpiston-cylinder unit (15).
 4. Device according to claim 1, wherein theforce exerted by the force mechanism (13) can be automaticallycontrolled as a function of the load being exerted on the segment by thecast strand (4).
 5. Device according to claim 4, wherein, as a functionof the load on the segment, the force being exerted by the forcemechanism (13) can be transmitted to the deflections of the support rolland the tie-bar to oppose the expected profile camber of the crosssection of Ehe strand (4 d).
 6. Device according to claim 1, wherein theforce exerted by the force mechanism (13) is adjustable on the floatingside (6) of the segment (1).
 7. Device according to claim 1, wherein theforce exerted by the force mechanism (13) is adjustable simultaneouslyon the fixed side (5) and on the loose side (6) of the two opposingsegment frames (5, 6).
 8. Device according to claim 1, wherein severalforce-exerting mechanisms (13) are assigned to each segment frame (5,6).
 9. Device according to claim 1, wherein a lengthwise cutting deviceis installed downline from the segments (1).
 10. Device according toclaim 1, comprising a computer configured for filing the characteristicdeformation curves (19) of a segment (1) in the form of tables, and forcalling up the force to be exerted by the force mechanism (13) fromstored values in correspondence with the load being exerted on thesegments.